Conventional telecommunications networks include two distinct communication pathways or subnetworks—a voice network and a signaling network. These two networks function in a cooperative manner to set up and tear down calls between users. As implied by its name, the voice network handles the transmission of voice (or user data) information between users. The signaling network has a number of responsibilities, which include call setup, call teardown, and database access. In simple terms, the signaling network facilitates the dynamic linking together of a number of discrete voice-type communication circuits such that a voice-type connection is established between the calling and called party. Additionally, the signaling network provides a framework through which non-voice-related information may be transported, with this data and transport functionality being transparent to the users. This signaling technique is often referred to as out-of-band signaling, where the term “band” implies voice band. The signaling protocol most commonly employed in communication networks around the world is the signaling system 7 (SS7) protocol.
From a hardware perspective, an SS7 network includes a plurality of SS7 nodes, generically referred to as signaling points (SPs), that are interconnected using signaling links, also referred to as SS7 links. At least three types of SPs are included in an SS7 network: service switching points (SSPs), signal transfer points (STPs) and service control points (SCPs). Within an SS7 signaling network, each SP is assigned an SS7 network address, which is referred to as a point code (PC).
An SSP is normally installed in Class 4 tandem or Class 5 end offices. The SSP is capable of handling both in-band signaling and SS7 signaling. An SSP can be a customer switch, an end office, an access tandem and/or a tandem. An STP routes signaling messages. STPs are usually installed as mated pairs for reliability purposes. Finally, SCPs control access to databases, such as 800 number translation databases, 800 number carrier identification databases, credit card verification databases, etc.
Signaling links are transmission lines used to connect SPs together. Conventional signaling links are dedicated bi-directional facilities operating at 56 kbps in the U.S. and Canada and at 64 kbps when clear channel capability is deployed. Normally, every link has a mate for redundancy and enhanced network integrity. It will be appreciated that in some cases, traditional 56 kbps dedicated SS7 signaling links may be replaced by high-speed, shared-bandwidth signaling links, such as IP or ATM signaling links.